1. Statement of the Technical Field
The inventive arrangements relate to communication networks. More particularly, the present invention relates to systems and methods for Dynamic Spectrum Access (“DSA”) or Dynamic Spectrum Management (“DSM”) within the communication networks (e.g., a cognitive network).
2. Description of the Related Art
In current practice, the Federal Communications Commission (“FCC”) licenses segments of a Radio Frequency (“RF”) energy spectrum (or wireless spectrum) to users in particular geographic areas. The licensed segments of the wireless spectrum include a Very High Frequency (“VHF”) band segment and an Ultra-High Frequency (“UHF”) band segment. In this regard, the wireless radio nodes of said users each utilize a fixed or preset segment of the wireless spectrum for RF communication purposes. These wireless radio nodes are referred to herein as Primary User Nodes (“PUNs”). Wireless radio nodes which are not permitted by such licensing to use one or more segments of the wireless spectrum are referred to herein as Secondary User Nodes (“SUNs”).
Studies have shown that 98% of the wireless spectrum is allocated in terms of licensing. The unallocated 2% of the wireless spectrum is left open for anyone to use as long as they follow certain power regulations. For example, the unallocated 2% of the wireless spectrum is used by Local Area Networks (“LAN”) and Bluetooth networks. Accordingly, the unallocated 2% of the wireless spectrum can be used by both the PUNs and the SUNs if they are suitably network enabled.
With the increased demand for personal wireless technologies, the unallocated portion of the wireless spectrum has become crowded. Consequently, various efforts have been made to address the overcrowding issue. One solution involves allowing SUNs to use licensed segments of the wireless spectrum, provided that any interference with the PUNs is minimal. Even though 98% of the wireless spectrum is licensed, only about 11% of the licensed portion of the wireless spectrum is actually utilized by the PUNs. Therefore, it is very possible that the SUNs' utilization of the licensed portion of the wireless spectrum results in minimal interference with PUN communications.
In view of the forgoing, efforts have been made in the field to configure SUNs for facilitating DSA/DSM (i.e., the management of licensed spectrum resources). In this regard, the SUNs are generally operative to sense licensed segments of the wireless spectrum. When a licensed segment of the wireless spectrum is sensed, the SUNs access and use that portion of the wireless spectrum as secondary users until communication activity by one or more PUNs therein is detected. Despite the advantages of this conventional DSA/DSM technique, it suffers from certain drawbacks. For example, collisions can frequently occur between PUN communications and SUN communications as a SUN finds a spectrum “hole” or spectrum “white space” (i.e., unused portion of a licensed wireless spectrum segment) and coordinates with its peer SUNs to use the spectrum “hole” or “whitespace”.
Typically, the PUNs and SUNs employ an Open Systems Interconnection (“OSI”) protocol stack. The OSI protocol stack generally comprises the following seven layers: (1) physical layer; (2) data link layer; (3) network layer; (4) transport layer; (5) session layer; (6) presentation layer; and (7) application layer. Each of these layers is well known in the art, and therefore will not be described in detail herein. In the cognitive network scenarios, the cognitive SUNs are each designed to include cognition or knowledge at just the physical layer of the OSI protocol stack for spectrum analysis purposes. In this regard, the SUNs implement a number of conventional physical layer spectrum sensing approaches to signal detection and/or various conventional rendezvous approaches for groups of SUNs to agree on the wireless spectrum to “borrow”. Despite the advantages of these conventional cognitive network approaches, they provide limited gains to solving the DSA/DSM problem.